In the past, a semi-finished blank for a varifocal lens was constituted so as to include a lower substrate whose front had a convex curved surface, and an upper substrate whose back had a concave curved surface and which was joined opposite this front. A varifocal section including a liquid crystal material was disposed between the upper and lower substrates. The refractive index of this varifocal section could be varied by applying voltage to the varifocal section, so the product could be used as a lens for bifocal eyeglasses, for example.
Patent Literature 1, for instance, discloses a method for manufacturing a semi-finished blank for a varifocal lens, in which, in the joining of an upper substrate and a lower substrate, the upper and lower substrates are stuck together and then an adhesive agent is introduced through one of two holes provided near the outer periphery of the upper substrate in a state in which the upper substrate has been pressed to the varifocal section via a pad, and air or the like is blown through the other hole so that the adhesive agent moves over all of both substrates.